exo·​sphere ˈek-sō-ˌsfir How to pronounce exosphere (audio)
: the outer fringe region of the atmosphere of the earth or a celestial body (such as a planet)
exospheric adjective

Examples of exosphere in a Sentence

Recent Examples on the Web The art from the winners will debut on the exosphere on July 4. Carolyn Giardina, Variety, 14 Mar. 2024 Objectives included study of the lunar exosphere, thermal properties and the amount of hydrogen in the lunar soil. George Petras, USA TODAY, 20 Jan. 2024 The scientific objectives of the Peregrine mission, according to NASA’s website, are to study the lunar exosphere, thermal properties, and hydrogen abundance of the lunar regolith, magnetic fields, and the radiation environment. Lily Larsen, Washington Examiner, 5 Dec. 2023 Advertisement The exosphere — the skin of the venue — will show real-time driver information during the race, along with live content and the postrace podium celebration. Sam Farmer, Los Angeles Times, 16 Nov. 2023 Additional plans call for Formula One content to be displayed on the exosphere during the race, while an afterparty for the drivers will be held at Sphere. Alex Weprin, The Hollywood Reporter, 21 Sep. 2023 The total amount of gas in the lunar exosphere is tiny, perhaps 100 tons in total. The Physics Arxiv Blog, Discover Magazine, 31 May 2023 One method of achieving this is to have a ballistic missile launch what’s called a hypersonic glide vehicle into the exosphere—a vehicle that’s then able to skip-glide just over the atmosphere, repeatedly bouncing off the dense air molecules below. Sébastien Roblin, Popular Mechanics, 8 June 2023 But each Apollo lander injected about 20 tons of gas into the exosphere in the form of rocket exhaust. The Physics Arxiv Blog, Discover Magazine, 31 May 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'exosphere.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


exo- + -sphere

First Known Use

1949, in the meaning defined above

Time Traveler
The first known use of exosphere was in 1949

Dictionary Entries Near exosphere

Cite this Entry

“Exosphere.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/exosphere. Accessed 21 Apr. 2024.

Kids Definition


exo·​sphere ˈek-sō-ˌsfi(ə)r How to pronounce exosphere (audio)
: the outermost region of the atmosphere of the earth or a planet

More from Merriam-Webster on exosphere

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